Sensors have been provided on pressure relief rupture discs with connections to indicator lights and alarm systems at a monitor station to advise an operator of the rupture of such a disc so that corrective procedures may be directed most expeditiously to the required location. One type of sensor which has been employed is of the open probe type which operates by conduction of current between a petal or portion of the rupture disc and a metal probe when electrical contact therebetween occurs during the rupture of the disc. In a closed probe type of sensor, both conductors of the sensor are carried in the probe, and the disc during rupture contacts and deforms the probe to establish conduction which may be detected.
The requirement for actual contact between a portion of the disc and the probe necessitates precise placement of the probe to assure reliability and even with such placement the disc may not move sufficiently during rupture to engage the probe or may break apart or shatter such that parts of the disc do not engage the probe at all. The probes are generally not suited for more than one use, and the mounting for such probes requires precise forming. Further, arcing during the establishment of electrical contact between the required parts in a conductive sensor type system must be safely contained if the sensor is to be used in the presence of flammable or explosive substances.